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ARTICLESBiawak, 10(1), pp. 13-17© 2016 by International Varanid
Interest Group
Observation in the Wild of the Poorly-Known Varanus yuwonoi
OLGA ILENKAYA1 & J. LINDLEY CKAY2
1Department of BiologyYoung Harris College
1 College StreetYoung Harris, Georgia 30582 USA
E-mail: [email protected]
25875 Brasstown Creek RoadYoung Harris, Georgia 30582 USA
E-mail: [email protected]
There is a great paucity of information about this species in
general, and its natural history in particular. Some of its natural
history has been described based on interviews with local people
(Harvey & Barker, 1998; Weijola, 2010), and Weijola (2010)
speculated on its ecology, hypothesizing a preference for ambush
hunting based on a low encounter rate in the wild and information
from local trappers indicating that the species can be
Here, we detail an observation of a wild V. yuwonoi
it extends the species’ known range, contributes information
about its habitat, and to our knowledge, is
Observation
We encountered a single V. yuwonoi on 25 January 2014 at
approximately 2100 h. The weather was overcast (typical of the
preceding four days) and approximately
Abstract - New information on Varanus yuwonoi is presented based
on an in situ observation. The known range on Halmahera is extended
south to Weda and an incidence of nocturnal activity is
documented.
Introduction
Varanus yuwonoi is a recently discovered monitor from the island
of Halmahera, Indonesia (Harvey & Barker, 1998) that remains
poorly known. This species is reported from only a few locations,
all on the north-
locality near Jailolo and nearby Tanah Putih (between
near the villages of Akesahu and Kao, on the western side of Kao
Bay (Weijola, 2010; Fig. 1). The habitat of three specimens was
described as primary and secondary lowland forest below 50 m asl
(Weijola, 2010), and the holotype was found between 50 – 300 m asl
(Harvey & Barker, 1998). The conservation status of V. yuwonoi
has yet to be assessed by the IUCN (IUCN, 2015), but is described
as rare by Koch et al. (2013). This attractive multi-hued monitor
is exported from Indonesia for the international pet trade (Koch et
al., 2013) and is harvested by local hunters (Weijola, 2010),
raising concerns about its vulnerability to overexploitation (Koch
et al., 2013).
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14BIAWAK VOL. 10 NO. 1
of Weda, on the north-eastern part of the southern
approximately equidistant along a footpath between Weda Resort
and Desa Kobe. On one side of the path the slope dropped a few
meters into a low, extensive mangrove forest, and on the other side
was a low ridge covered with secondary rainforest, rising and then
descending to the coast within about 50 m. The monitor was detected
by the sound of its movement and was
ground from near the mangrove edge upslope through the
rainforest towards the ridge top and coast. Its manner was
consistent with typical foraging behavior of monitors during
daylight, moving leisurely, seeming alert and unalarmed. The size
of the specimen was estimated at SV 450 mm and a number of
photographs were taken (Figs. 2-4).
Discussion
The habitat recorded here is consistent with previous V. yuwonoi
(Weijola, 2010). Since tropical
rainforest is the predominant vegetation cover of the
island, it is reasonable to speculate that V. yuwonoi may be
distributed across the entire island of Halmahera. However, until
now, all specimens were known only
extends the known range south toward the northern end of Weda
Bay. Although all members of the family Varanidae are primarily
diurnal (Bennett, 1998), there are a number of reports of nocturnal
activity amongst monitors (Irwin et al., 1996; Trembath, 2000; Cota
et al., 2008; Rhind et al., 2013). In many cases these appear to
document atypical behavior; however, some recent studies have
revealed that monitors can incorporate nocturnal activity into
their lifestyles (Uyeda et al., 2013; Rismiller et al., 2010). Two
individuals of V. salvator on Tinjil Island, Indonesia actively
foraged in the hours between 0128 and 0525 h, and this may be a
mechanism imparting a foraging advantage over other individuals
foraging only by day (Uyeda et alRismiller et al. (2010), in their
detailed examination of the reproductive biology of V. rosenbergi,
found that
hours after nightfall. These studies and our observation suggest
that some monitors have the ability, both at
showing documented locations of Varanus yowonoi.
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15
Fig. 2. Varanus yuwonoi, near Weda, Halmahera, Indonesia.
Photographed by J. Lindley McKay.
Fig. 3. Head and body of Varanus yuwonoi, near Weda, Halmahera,
Indonesia. Photographed by Olga Milenkaya.
VARANUS YUWONOI
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158.
of blue-tailed monitor lizard (genus Varanus) from Halmahera
Island, Indonesia. Herpetologica. 54(1): 34-44.Irwin, S., B. Lyons
& T. Frisby. 1996. Nocturnal activity by Varanus panoptes
Herpetofauna. 26: 50.IUCN. 2015. The IUCN Red List of Threatened
Species. Version 2015-4. www.iucnredlist.org. Last accessed: 23
December 2015.
2013. Pressing problems: Distribution, threats, and conservation
status of the monitor lizards (Varanidae: Varanus spp.) of
Southeast Asia and the Indo-Australian Archipelago. Herpetological
Conservation and Biology. 8: 1-62.Rhind, D., J. S. Doody, R. Ellis,
A. Ricketts, G. Scott,
Varanus glebopalma activity and foraging. Herpetological Review.
44(4): 687-688.Trembath, D. 2000. Nocturnal activity by Goulds
monitor (Varanus gouldii) at Town Common
BIAWAK VOL. 10 NO. 1 16
an individual and population level, to engage in some degree of
nocturnal activity.
of V. yuwonoi is needed. This and other species in the
conservation and management decisions can be made.
Acknowledgements - We thank Rob and Linda Sinke of Weda Resort
for their generosity and ongoing
at Weda Resort for extending their warmth and hospitality to us
during our stay. We also thank Sam Sweet and Valter Weijola for
their reviews and assistance, resulting in the improvement of this
manuscript.
References
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Biawak. 2(4): 152-
Fig. 4. Head of Varanus yuwonoi, near Weda, Halmahera,
Indonesia. Photographed by Olga Milenkaya.
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17
Environmental Park, Townsville Queensland. Herpetofauna. 30(2):
52-52.Uyeda, L., E. Iskandar, A. Wirsing & R. Kyes. 2013.
Nocturnal activity of Varanus salvator on Tinjil Island, Indonesia.
Biawak. 7(1): 25-30.
Weijola, V.S.A. 2010. Geographical distribution and habitat use
of monitor lizards of the north
VARANUS YUWONOI
Received: 23 December 2015; Accepted: 27 May 2016